free-wheeling (adj.)youdaoicibaDictYouDict[free-wheeling 词源字典]
also freewheeling, 1903, from free wheel (1899, see free (adj.) + wheel (n.)); a bicycle wheel that turns even when not being pedaled, later from the name of a kind of automobile drive system that allowed cars to coast without being slowed by the engine. Figurative sense is from 1911.[free-wheeling etymology, free-wheeling origin, 英语词源]
slow (v.)youdaoicibaDictYouDict
1550s, "make slower;" 1590s, "go slower," from slow (adj.). Related: Slowed; slowing. Old English had slawian (intransitive) "to be or become slow, be sluggish," but the modern use appears to be a 16c. re-formation.